{"references": ["DRACKLEY, J.K.: Biology of dairy cows during the transition period: the final frontier? J. Dairy Sci., 82:2259-2273, 1999.", "GOFF, J.P.: Major advances in our understanding of nutritional influences on bovine health. J. Dairy Sci., 89:1291-1301, 2006.", "HORVAT, J., KIROVSKI, DANIJELA, \u0160AMANC, H., DIMITRIJEVI\u0106, B., KI\u0160KAROLJ, F., BE\u010cKEI, \u017d., KILIBARDA, NATA\u0160A: Procena energetskog statusa krava sa podru\u010dja Subotice odre\u0111ivanjem organskih sastojaka mleka. Zbornik radova XI regionalnog savetovanja iz klini\u010dke patologije i terapije \u017eivotinja \"Clinica Veterinaria 2009\", Subotica, 19.-21. jun, 2009, 99-101.", "HORVAT, J., \u0160AMANC, H., KIROVSKI, DANIJELA, KATI\u0106, VERA (2007): Zdravstveni poreme\u0107aji visokomle\u010dnih krava u ranoj fazi laktacije i uticaj na higijensku ispravnost sirovog mleka, Veterinarski specijalisti\u010dki institut Subotica", "JONKER, J.S., KOHN, R.A.: Using milk urea nitrogen to evaluate diet formulation and environmental impact on dairy farms. Scientific World Journal, 18, Suppl. 2., 852-859, 2001.", "JOVI\u010cIN, M., \u0160AMANC, H., MILOVANOVI\u0106, A., KOVA\u010cEVI\u0106, MIRA: Odre\u0111ivanje telesne kondcije \u017eivotinja. Zbornik radova IV simpozijuma \"Ishrana, reprodukcija i za\u0161tita zdravlja goveda \u2013 Etiopatogeneza i dijagnostika poreme\u0107aja metabolizma reprodukcije goveda\", Subotica, 27. septembar \u2013 01. oktobar, 2005., 217-231.", "KAMPL, B.: Pokazatelji energetskog deficita mle\u010dnih krava u mleku i njihovo kori\u0161\u0107enje u programu zdravstvene preventive i intenziviranja proizvodnje i reprodukcije. Zbornik radova IV simpozijuma \"Ishrana, reprodukcija i za\u0161tita zdravlja goveda \u2013 Etiopatogeneza i dijagnostika poreme\u0107aja metabolizma reprodukcije goveda\", Subotica, 27. septembar \u2013 01. oktobar, 2005., 261-267.", "KIROVSKI, DANIJELA, \u0160AMANC, H., PRODANOVI\u0106, R.: Procena energetskog statusa krava na osnovu koncentracije masti, proteina i uree u mleku, Veterinarski glasnik, 66:1-2,97-110, 2012.", "MARENJAK, T.S., POLJI\u010cAK-MILAS, NINA, STOJEVI\u0106, Z.: Svrha odre\u0111ivanja koncentracije ureje u kravljem mlijeku. Praxis Veterinaria, 52:233-241, 2004.", "MULLIGAN, F., O'GRADY, L., RICE, D., DOHERTY, D.: Production disease of the transition cow: Body condition score and energy balance. Irish Veterinary Journal, 59(9)505-510, 2006.", "SAVI\u0106, \u0110., KASAGI\u0106, D., JOTANOVI\u0106, STOJA, MATARUGI\u0106, D., \u0160ARI\u0106, M., MIJATOVI\u0106, R.: Procjena energetskog statusa krava u ranoj laktaciji na osnovu odre\u0111ivanja organskih sastojaka mlijeka. Agroznanje, 12(1)67-74, 2011.", "SAVI\u0106, \u0110., MATARUGI\u0106, D., DELI\u0106, N., KASAGI\u0106, D., STOJANOVI\u0106, M.: Odre\u0111ivanje organskih sastojaka mleka kao metoda ocene energetskog statusa mle\u010dnih krava. Veterinarski glasnik, 64:1-2, 21-32, 2010.", "SINOVEC, Z.: Uloga ishrane u etiopatogenezi zdravstvenih poreme\u0107aja krava u peripartalnom periodu. Veterinarski glasnik 57, 3-4, 137-148. 2003.", "STAMATOVI\u0106, S., \u0160AMANC, H., JOVANOVI\u0106, M.: Uporedno ispitivanje koncentracije glikoze u krvi v. auricularis magna i v. subcutanea abdominis mle\u010dnih krava. Veterinarski glasnik, 37(4)243-256, 1983.", "\u0160AMANC, H., KIROVSKI, DANIJELA, DIMITRIJEVI\u0106, B., VUJANAC, I., DAMNJANOVI\u0106, Z., POLOVINA, M.: Procena energetskog statusa krava u laktaciji odre\u0111ivanjem organskih sastojaka mleka. Veterinarski glasnik, 60(5-6)283-297, 2006.", "\u0160AMANC, H., SINOVEC, Z., CERNESCU, H. (2005): Osnovi poreme\u0107aja energije visokomle\u010dnih krava. Zbornik radova IV simpozijuma \"Ishrana, reprodukcija i za\u0161tita zdravlja goveda \u2013 Etiopatogeneza i dijagnostika poreme\u0107aja metabolizma reprodukcije goveda\", Subotica, 27. septembar \u2013 01. oktobar, 2005., 89-101."]}

The aim of the study was to evaluate the energy status of cows (n=132) based on the concentration of organic milk constituents during early lactation. Cows were divided into three groups according to the stage of lactation (group A, n=43, 15-30 DIM; group B, n=33, 31-45 DIM; group C, n=56, 46 to 60 DIM). Concentrations of milk fat and protein and the milk fat: protein ratio tended to decrease, and the concentration of urea had increased towards to the end of the evaluated period. Statistically significant differences were found in concentrations of milk fat (41.58±37.15 vs. 37.15±3.63 and 36.11±4.57 g/L, respectively), urea (2.86±0.50 vs. 3.48±0.69 and 3.61±0.56 mmol/L, respectively) in all three groups, and milk fat : protein ratio in the group A compared to the other two groups, and also in lactose concentration between groups A and B (47.14±01.29 vs. 47.71±1.4 g/L). The ratio of the concentration of milk fat and protein, as well as relations between urea and protein showed a strong energy deficit in all tested cows, with more or less pronounced deficit or relative surplus of protein. Such condition negatively affects health status and milk production of evaluated cows, as well as their reproductive performance.